Assessment of the daily ragweed pollen concentration with previous-day meteorological variables using regression and quantile regression analysis for Szeged,Hungary

Time-varying parametric linear and time-varying nonparametric regression models as well as a time-varying nonparametric median regression model are developed to predict the daily pollen concentration for Szeged in Hungary using previous-day meteorological parameters and the daily pollen concentration. The models are applied to rainy days and non-rainy days, respectively. The most important predictor is the previous-day pollen concentration level, and the only other predictor retained by a stepwise regression procedure is the daily mean global solar flux for rainy days and the daily mean temperature for non-rainy days. Although the variance percentage explained by these two predictors is higher for non-rainy (55.2%) days than for rainy (51.9%) days, the prediction rate is slightly better for rainy than for non-rainy days. Nonparametric regression yields substantially better estimates, especially for rainy days indicating a nonlinear relationship between the predictors and the pollen concentration. The explained variance percentage is 71.4 and 64.6% for rainy and non-rainy days, respectively. Concerning the mean absolute error, the nonparametric median regression provides the best estimate. The quantile regression shows that probability distribution of daily ragweed concentration is much more skewed for non-rainy days, while the more concentrated probability distribution for rainy days exhibits relatively stable ragweed pollen concentrations. The possible lowest limits of concentrations are also calculated. Under highly favorable conditions for peak concentrations, the pollen level reaches at least 350 grains m⁻³ and 450 grains m⁻³ for rainy and non-rainy days, respectively. These values again underline the excessive ragweed pollen load over the area of Szeged.     

Using meteorologic data to predict daily ragweed pollen levels

Pollen-related allergy is a common disease resulting in symptoms of hay fever and asthma. Control of symptoms depends (generally) on avoidance and pharmacological treatment. Both of these approaches could benefit from accurate predictions of pollen levels for future days. We have constructed a model that uses meteorological data to predict ragweed pollen levels based on air samples collected daily in Kalamazoo, MI from 1991 to 1994. Ragweed pollen counts were converted to pollen grains/m³ of air (24-h average). We used Poisson regression, which appropriately handles the heterogenous variance associated with pollen data. Using standard statistical model selection procedures, combined with biological considerations, we selected rainfall, wind speed, temperature, and the time measured from the start of the season as the most significant variables. Using our model, we propose a method that uses the weather forecast for the following day to predict the ragweed pollen level. This approach differs from most previous attempts because it uses Poisson regression and because this model needs to be fit iteratively each day. By updating the coefficients of the model based on the information to date, this method allows the fundamental shape of the pollen distribution curve to change from year to year. Application to the Kalamazoo data suggests that the method has good sensitivity and specificity for predicting high pollen days.     

Forecasting ragweed pollen characteristics with nonparametric regression methods over the most polluted areas in Europe

Nonparametric time-varying regression methods were developed to forecast daily ragweed pollen concentration, and the probability of the exceedance of a given concentration threshold 1 day ahead. Five-day and 10-day predictions of the start and end of the pollen season were also addressed with a nonparametric regression technique combining regression analysis with the method of temperature sum. Our methods were applied to three of the most polluted regions in Europe, namely Lyon (Rhône Valley, France), Legnano (Po River Plain, Italy) and Szeged (Great Plain, Hungary). For a 1-day prediction of both the daily pollen concentration and daily threshold exceedance, the order of these cities from the smallest to largest prediction errors was Legnano, Lyon, Szeged and Legnano, Szeged, Lyon, respectively. The most important predictor for each location was the pollen concentration of previous days. The second main predictor was precipitation for Lyon, and temperature for Legnano and Szeged. Wind speed should be considered for daily concentration at Legnano, and for daily pollen threshold exceedances at Lyon and Szeged. Prediction capabilities compared to the annual cycles for the start and end of the pollen season decreased from west to east. The order of the cities from the lowest to largest errors for the end of the pollen season was Lyon, Legnano, Szeged for both the 5- and 10-day predictions, while for the start of the pollen season the order was Legnano, Lyon, Szeged for 5-day predictions, and Legnano, Szeged, Lyon for 10-day predictions.     

Ragweed (Ambrosia) sensitisation rates correlate withthe amount of inhaled airborne pollen. A 14-year studyin Vienna, Austria

Ragweed pollen have been monitored since 1976 inVienna. Since 1984, the outdoor patients of theallergy department of the ear-nose-and-throatUniversity Clinic underwent both Skin Prick Test andRAST/CAP test with a standard series of commoninhalant allergens, ragweed (Ambrosia elatiorL.) included. Both the ragweed counts and the number of positiveRAST results showed a significant increase by time.Furthermore, a clear correlation between the number ofairborne pollen and the percentage of positiveRAST/CAP results is evident.The immune-response in the Viennese population ofatopic subjects is dependent on the amount of inhaledpollen.     

Ragweed in Australia

Ragweed (Ambrosia spp.) is awell-recognised cause of fall allergic rhinitisand seasonal asthma in the Northern Hemispherecountries of United States and Canada. InAustralia the appearance of ragweed (Ambrosia artemisiifolia) was first recordedduring the 1930s in Queensland, ragweed hayfeverwas noted in 1959 and ragweed dermatitisdocumented in 1963. Aerobiology studies performedin the capital cities of Eastern and WesternAustralia have not demonstrated ragweed pollen.This study, performed in two towns in theNorthern Rivers area of New South Wales, closeto the Queensland border, documents the ragweedseason between November 1996 and December 1997in one of the towns, by monitoring the air usinga Burkard 7-day spore trap. Two hundred and sixvolunteers were skin tested to a range ofaeroallergens including pollen of ragweed (Ambrosia artemisiifolia) and Tibouchina, a treeflowering at the same time as ragweed. 34% ofvolunteers were skin prick test positive toragweed and 5.4% to Tibouchina. The ragweedseason commenced in the first week of March andextended to early May, with the peak day pollencount, 483/m³, present in the first week ofApril. Although many residents blamed thespectacular purple Tibouchina flowers for latesummer respiratory symptoms, most were sensitiveto ragweed and not Tibouchina.     

Ragweed in the Czech Republic

During the last years, a well documented expansion ofragweed (Ambrosia artemisiifolia L., Ambrosia trifida L.) over the Mediterranean andtemperate Europe has been in progress. The currentdistribution of ragweed plants in the Czech Republicis summarized and the ragweed pollen concentration asmonitored by 12 pollen stations in the country isdiscussed. The present situation in the ragweed pollensensitization among children and adults with pollenallergy in Brno is described. So far no dangerousexpansion of ragweed plants in our country has beenobserved. Ragweed pollen concentration is occasionallysignificant in the Brno station only, other pollenstations are reporting insignificant amounts ofragweed pollen during August-September periods,although there has been a steady increase in ragweedpollen concentration in the Prague area over the lastfive years. Skin prick tests and/or specific IgEmeasurements with ragweed allergen were performed on94 children with pollen allergy in the Brno region in1995 and on 206, 210 and 229 adult allergic patientsin 1995, 1996 and 1997, respectively. Positive skinreaction or positive specific IgE to ragweed was foundin 22% children and in 25% (1995), 19% (1996) and 25% (1997) adults with pollen allergy. It isconcluded that ragweed does not seem to represent anyimminent major threat to the allergic population inthe Czech Republic until now, however, it remains apotentially very dangerous allergen.     

Monitoring of <Emphasis Type="Italic">Ambrosia</Emphasis> pollen concentration in the atmosphere of Bratislava (Slovakia) during years 2002–2007

Ambrosia pollen represents a significant allergenic risk for pollen-sensitive people also in Slovakia. The aim of this study was to compare the results of the monitoring of Ambrosia pollen concentrations and pollen seasons in Bratislava during years 2002–2007. Measurements were performed by the volumetric method using Burkard volumetric spore trap at the height of 10 m above ground level. During six monitored years, a total of 11,334 Ambrosia pollen grains per cubic meter of air were recorded. The highest total ragweed pollen amount was detected in 2002 (2,577 pollen grains of the total annual pollen concentration) and the lowest ragweed pollen concentration (1,213 pollen grains) was determined in 2007. However, mentioned year was represented as the year with the longest pollen season among the all monitored years in Bratislava (41 days). The pollen season peak day of 2002, 2004, 2005 and 2006 was recorded at the beginning of September; in 2003 and 2007 the peak was at the second half of August. The highest daily amount of Ambrosia pollen grains (more than 100 grains per cubic meter of air) was in 2002 (12 days). The results can be utilized to help to prevent symptoms of allergic reactions to Ambrosia pollen and improve quality of life during seasonal allergic diseases in ragweed pollen-sensitive people.     

A new weather factor predicting airborne pollen concentration: Péczely’s macrosynoptic weather types

In the present study determinative factors for ragweed (Ambrosia elatior) pollination were studied in Budapest between 1991 and 1996. The aim was to create a model to predict the day-to-day pollen count variation. The pollen concentration is determined mostly by the potential concentration and the mean concentration of the three previous days. These two variables can explain 56% of the total variance. Daily mean and maximum temperature, daily temperature fluctuation and the number of hours of sunshine in the previous day have a significant positive effect on the pollen count. The amount of precipitation on the previous day, relative humidity on the actual and on the previous day influence it negatively. When a cyclone prevails, pollen concentration is usually lower than the seasonal average. Some anticyclonal situations have a similar effect, while other anticyclonal types promote pollination. A predictive model was then created by multiple regression using the potential concentration, the mean concentration of the three previous days, the daily temperature fluctuation and the synoptic type as independent variables. This model can explain more than 68% of the total variance, and its accuracy is >71%. The model seems to predict accurately the trends during the pollen seasons, thus it will probably be a good tool in the practical prediction in Budapest, and the methodology will hopefully be applicable to other sites of the Carpathian Basin too.     

The occurrence of Ambrosia pollen in Rzeszów,Kraków and Poznań, Poland: investigation of trends and possible transport of Ambrosia pollen from Ukraine

Previous studies have shown that ragweed pollen arrives in Poland from sources in the south, in Slovakia, the Czech Republic, Hungary and Austria. It is likely that ragweed pollen also arrives from sources in the southeast (e.g. Ukraine). This hypothesis was investigated using 13 years of pollen data and back-trajectory analysis. Ambrosia pollen data were collected at three sites in Poland, Rzeszów, Kraków and Poznań. The amount of ragweed pollen recorded at Rzeszów was significantly higher than in Poznań and Kraków. This can be related to either a higher abundance of local populations of Ambrosia in south-east Poland or the proximity of Rzeszów to foreign sources of ragweed pollen. The combined results of pollen measurements and air mass trajectory calculations identified plumes of Ambrosia pollen that were recorded at Rzeszów, Kraków and Poznań on 4 and 5 September 1999 and 3 September 2002. These plumes arrived at the pollen-monitoring sites from an easterly direction, indicating sources of Ambrosia pollen in eastern Poland or Ukraine. This identifies Ukraine as a possible new source of ragweed pollen for Poland and therefore an important source area of Ambrosia pollen on the European Continent.     

三裂叶豚草雄花序分化的气候效应分析

【背景】三裂叶豚草是一种外来恶性杂草,它的入侵不仅影响当地的生物多样性和生态系统,而且给农牧业造成巨大的经济损失。此外,其花粉量大,是引起人体一系列过敏反应的致敏源。【方法】通过对2008～2010年三裂叶豚草分化时期和气象因素进行调查,以当年分化开始前一个月至分化结束的日最高气温、日最低气温、日平均气温、相对湿度、日照时间等数据,分析影响三裂叶豚草雄花序分化的气象因子。【结果】雄花序从未分化期至成熟期平均需26d。三裂叶豚草营养生长后期,较短的日照时间和日平均气温、较高的相对湿度和较大的温差等环境条件有利于三裂叶豚草雄花序较早地开始分化。而在分化早期,长时间较高的相对湿度不利于雄花序的分化。【结论与意义】外界环境的变化能够影响三裂叶豚草雄花序的分化,对其分化开始时间起决定性作用。本研究为制定合理的三裂叶豚草防治措施提供了理论依据,同时为进一步研究其生物安全性提供了参考。     

Exploring the spatio-temporal relationship between two key aeroallergens and meteorological variables in the United Kingdom

Constructing accurate predictive models for grass and birch pollen in the air, the two most important aeroallergens, for areas with variable climate conditions such as the United Kingdom, require better understanding of the relationships between pollen count in the air and meteorological variables. Variations in daily birch and grass pollen counts and their relationship with daily meteorological variables were investigated for nine pollen monitoring sites for the period 2000–2010 in the United Kingdom. An active pollen count sampling method was employed at each of the monitoring stations to sample pollen from the atmosphere. The mechanism of this method is based on the volumetric spore traps of Hirst design (Hirst in Ann Appl Biol 39(2):257–265, 1952). The pollen season (start date, finish date) for grass and birch were determined using a first derivative method. Meteorological variables such as daily rainfall; maximum, minimum and average temperatures; cumulative sum of Sunshine duration; wind speed; and relative humidity were related to the grass and birch pollen counts for the pre-peak, post peak and the entire pollen season. The meteorological variables were correlated with the pollen count data for the following temporal supports: same-day, 1-day prior, 1-day mean prior, 3-day mean prior, 7-day mean prior. The direction of influence (positive/negative) of meteorological variables on pollen count varied for birch and grass, and also varied when the pollen season was treated as a whole season, or was segmented into the pre-peak and post-peak seasons. Maximum temperature, sunshine duration and rainfall were the most important variables influencing the count of grass pollen in the atmosphere. Both maximum temperature (pre-peak) and sunshine produced a strong positive correlation, and rain produced a strong negative correlation with grass pollen count in the air. Similarly, average temperature, wind speed and rainfall were the most important variables influencing the count of birch pollen in the air. Both wind speed and rain produced a negative correlation with birch pollen count in the air and average temperature produced a positive correlation.     

Ambrosia elatior (L.) in Hungary (1989–1990)

Summary Weeds and among themAmbrosia are probably the most important vascular plants related to pollinosis in Hungary. Sampling was carried out in central (Budapest) and in southern (Paks, Szeged) Hungary. The results of two years (1989–1990) of aerobiological study onAmbrosia airborne pollen are reported. The highest percentage of airborne pollen was found in the mid-August to mid-September period, having a good correlation with clinical data on pollinosis. The implications of these results are considered in the context of forecasting and prevention of seasonal ragweed pollinosis.     

Some details about ragweed airborne pollen in Hungary

Ambrosia elatior – the only species living inHungary – appeared at the beginning of this centuryon the southern border of the country, along theDanube. Since then, unfortunately, it has become themost common weed in Hungary, and the quantity of itspollen is many times higher than the European average(Jäger, 1998; Juhász, 1998). Based on theresults of our ten-year (1989–1998) monitoring inHungary, there is no doubt than more than 60% of latesummer-early autumn pollen originates from ragweed,causing the most serious pollinosis in Hungary. Thequantity and ratio of ragweed pollen is much higherand the length of Ambrosia pollen season islonger in the southern than in the northern part ofHungary.     

Daily Ambrosia Pollen Concentration in the Air of Ankara,Turkey (1990-1999)

The airborne ragweed pollen spectrum was investigated in the air of Ankara, Turkey for aperiod of ten years (1990-1999) using a Burkard seven-day volumetric recording trap. In our study period,long distance transported Ambrosia pollen has been registered. Daily pollen levels varied from low to highin Burge's system. In last three years, the pollen concentration of Ambrosia showed a clear increasingtendency. Our results prove that ragweed pollen may be an important threat for ragweed sensitive patientsin Ankara city in near future.     

Airborne pollen of Ambrosia in Burgundy (France) 1996–1997

Pollen counts in Burgundy were monitored by means of four Hirst volumetric traps. Their analysis revealed a sharp rise of Ambrosia from 1996 to 1997. The minimum amount of ragweed pollen likely to provoke allergies (13 grains m–3) was reached or exceeded several days every year, but without leading to clinical symptoms. The circadian variation of Ambrosia pollen showed two peaks: the first one in the morning was suggested to coincide with local pollination, although the second one, in the afternoon, seemed to result from a long range transport which was confirmed by the study of wind roses.     

Estimating extreme daily pollen loads for Szeged, Hungary using previous-day meteorological variables

The aim of this paper is to analyse how meteorological elements relate to extreme Ambrosia pollen load on the one hand and to extreme total pollen load excluding Ambrosia pollen on the other for Szeged, Southern Hungary. The data set comes from a 9-year period (1999–2007) and includes previous-day means of five meteorological variables and actual-day values of the two pollen variables. Factor analysis with special transformation was performed on the meteorological and pollen load data in order to find out the strength and direction of the association of the meteorological and pollen variables. Then, using selected low and high quantiles corresponding to probability distributions of Ambrosia pollen and the remaining pollen loads, the quantile and beyond-quantile averages of pollen loads were compared and evaluated. Finally, a nearest neighbour (NN) technique was applied to discriminate between extreme and non-extreme pollen events using meteorological elements as explaining variables. The observed below or above quantile events are compared with events obtained from NN decisions. The number of events exceeding the quantile of 90% and not exceeding that of 10% is strongly underestimated. However, the procedure works well for quantiles of 20 and 80%, and even better for those of 30 and 70%. Using a nearest neighbour technique, explaining variables in decreasing order of their influence on Ambrosia pollen load are temperature, global solar flux, relative humidity, air pressure and wind speed, while on the load of the remaining pollen are temperature, relative humidity, global solar flux, air pressure and wind speed.     

Meteorological factors affecting daily urticaceae pollen counts in southwest Spain

The influence of meteorological factors on daily Urticaceae pollen counts were studied in Córdoba (southwest Spain) in 1996 and 1997. The daily Urticaceae pollen concentrations were obtained by using a Hirst-type volumetric sampler, and meteorological data were obtained from the Córdoba airport, located near the sampling site. The highest correlation between pollen concentration and meteorological parameters was obtained during non-rainy seasons. Temperature was found to be the most important meteorological parameter influencing pollen counts in spring, as temperature is the main reason for the increase of pollen concentration in the atmosphere. In autumn, humidity was another important parameter influencing pollen counts. Rain, however, did not appear to be significant. The influence of the pollen concentration of the 2 previous days and the pollen concentration of the previous day has been studied. During periods with low precipitation, the pollen concentration of the previous day was a useful predictor of Urticaceae pollen concentrations for the following day. Received: 4 January 1999 / Revised: 26 July 1999 / Accepted: 6 September 1999     

Effect of meteorological events on ragweed pollen count

Hourly and daily counts of air-borne ragweed pollen, AMBROSIA SPP, taken with a volumetric sampler during the 1961 season at Ottawa, Canada, were compared with meteorological events. The time of daily peak concentration of pollen coincided with the time of decreasing relative humidity and development of a super-adiabatic lapse rate in the first 200 ft of atmosphere. Daily variations in pollen count were virtually completely dominated by the local ragweed population and microclimate but could be explained to a limited extent by variations in air mass.On occasions, gravity slide counts using a Durham type apparatus varied qualitatively with volumetric counts, but it was not possible to obtain a constant factor to convert gravity to volumetric counts.

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Zusammenfassung Die stündliche und tÄgliche Anzahl von Pollen des Jakobskreuzkrauts(AMBROSIA SPP.) in der Luft (mit einem volumeterischen Sammler bestimmt) wÄhrend der Saison 1961 in Ottawa, Kanada, wurde mit meteorologischen Daten korreliert. Die höchste Pollenzahl in der Luft fiel mit dem Abfall der rel. Feuchte zusammen und der Entwicklung eines überadiabatischen Gradienten in den ersten 65 m Höhe der AtmosphÄre. Die tÄglichen Schwankungen der Pollenzahl wurden tatsÄchlich vollstÄndig von der lokalen Verteilung der Ambrosia spp. und dem Mikroklima bestimmt und konnten nur in geringem Masse mit den Schwankungen der Luftmassen in Zusammenhang gebracht werden.Die Zahl der Pollen in durch Schwerkraft gewonnen Proben fiel gelegentlich qualitativ mit den volumetrisch gewonnen Proben zusammen; es war jedoch nicht möglich, einen konstanten Faktor zu berechnen, um gravimetrisch gewonnene Werte in volumetrische umzuwandeln.

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Résumé Le nombre par heure et par jour, des grains de pollen de AMBROSIA SPP. dans l'air, mesuré par un collecteur volumétrique pendant la saison 1961 à Ottawa (Canada)a été comparé avec les données météorologiques.Le nombre le plus élevé correspondait à une chute de l'humidité relative et à un gradient superadiabatique s'élevant jusqu'à 65m d'altitude. La cause des variations quotidienne du nombre des grains de pollen correspondait pratiquement à la distribution locale de Ambrosia spp. et au microclimat, et ne correspondait que dans une faible mesure avec les déplacement des masses d'air. Le nombre des grains de pollen obtenus par gravitation au moyen d'un appareil du type Durham coincidait parfois qualitativement aux valeurs obtenues par un collecteur volumétrique, mars il n'a pas été possible d'établir un facteur constant,qui permÎt de transformer les valeurs gravimétriques en valeurs volumétriques.

     

Modeling the dispersion of Ambrosia artemisiifolia L. pollen with the model system COSMO-ART

Common ragweed (Ambrosia artemisiifolia L.) is a highly allergenic plant that is spreading throughout Europe. Ragweed pollen can be transported over large distances by the wind. Even low pollen concentrations of less than 10 pollen m(-3) can lead to health problems in sensitive persons. Therefore, forecasting the airborne concentrations of ragweed pollen is becoming more and more important for public health. The question remains whether distant pollen sources need to be considered in reliable forecasts. We used the extended numerical weather prediction system COSMO-ART to simulate the release and transport of ragweed pollen in central Europe. A pollen episode (September 12-16, 2006) in north-eastern Germany was modeled in order to find out where the pollen originated. For this purpose, several different source regions were taken into account and their individual impact on the daily mean pollen concentration and the performance of the forecast were studied with the means of a 2?×?2 contingency table and skill scores. It was found that the majority of the pollen originated in local areas, but up to 20% of the total pollen load came from distant sources in Hungary. It is concluded that long-distance transport should not be neglected when predicting pollen concentrations.     

Predicting the grass pollen count from meteorological data with regard to estimating the severity of hayfever symptoms in Melbourne (Australia)

In Melbourne, Australia, grass pollen is the predominant cause of hayfever in late spring and summer. The grass pollen season has been monitored in Melbourne, using a Burkard spore trap, for 13 years (1975–1981, 1985 and 1991–1997). Total counts for grass pollen were highly variable from one season to the next (approximately 1000 to >8000 grains/m³). The daily grass pollen counts also showed a high variability (0 to approximately 400 grains/m³). In this study, the grass pollen counts of the 13 years (12 grass pollen seasons, extending from October to January) have been compared with meteorological data in order to identify the conditions that can determine the daily amounts of grass pollen in the air. It was found that the seasonal total of grass pollen was directly correlated with the rainfall sum of the preceding 12 months (1 September–31 August): seasonal total of grass pollen (counts/m³)=18.161 × rainfall sum of the preceding 12 months (mm) −8541.5 (r _s=0.74,P<0.005,n=12). The daily amounts of grass pollen in the air were positively correlated with the corresponding daily average ambient temperatures (P<0.001). The daily amount of grass pollen which was to be expected with a certain daily average temperature was linked to the seasonal total of grass pollen: in years with high total grass pollen counts, a lower daily average temperature was required for a high daily pollen count than in years with low total grass pollen counts. As the concentration of airborne grass pollen determines the severity of hayfever in sensitive patients, an estimation of daily grass pollen counts can provide an indication of potential pollinosis symptoms. We compared daily grass pollen counts with the reported symptomatic responses of hayfever sufferers in November 1985 and found that hayfever symptoms were significantly correlated to the grass pollen counts (P<0.001 for nasal,P<0.005 for eye symptoms). Thus, a combination of meteorological information (i.e. rainfall and temperature) allows for an estimation of the potential daily pollinosis symptoms during the grass pollen season. Here we propose a symptom estimation chart, allowing a quick prediction of eye and nasal symptoms that are likely to occur as a result of variations in meteorological conditions, thus enabling both physicians and patients to take appropriate avoidance measures or therapy.